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Range Science 101: Weed control options for pastures

As you look forward to getting cows onto summer range, you might notice that a lot of the green you are seeing is weeds in your native range, especially cheatgrass and Japanese brome

As you look forward to getting cows onto summer range, you might notice that a lot of the green you are seeing is weeds in your native range, especially cheatgrass and Japanese brome.

These two species probably cause more irritation to grazing managers than any other undesirable species out there. Weeds in general are a bane to good grass management as they use up precious moisture that could be used for grass growth later on in the summer and they confiscate priceless nutrients from the soil profile.

Many of these weeds, like cheatgrass and Japanese brome, can develop so much growth that they restrict the early development or crowd out the desirable grass species. But what makes these weed species especially difficult to manage is the fact that they are annuals. They shoot up out of the ground about two weeks before any other plant out there, soak up the lions share of the moisture and nutrients, and then set seed and are fully mature within a couple of weeks.

Fortunately though, there are several control options we can use to take advantage of the growth habit of these weed species and limit the damage they do to our forage resource.

Chemical Control
Cheatgrass and Japanese brome generally green-up at least two weeks before our key forage species. This provides some unique opportunities to control them using herbicides. Glyphosate can be used to control these species, however, treating early to eliminate cheatgrass and Japanese brome before perennial grass species emerge is risky and therefore, is not recommended on range and pasture.

A better option would be to use Plateau at a rate of 4-12 oz + a surfactant at 1 qt./A early in the season and possibly again in the fall if necessary. Consult the manufacturer’s label for proper application instructions.

Prescribed Burning
In some areas, prescribed burning may be a much more cost effective method of control than chemical treatment. Timing of the burn is critical to effective control. Burning in the early spring when cheatgrass and Japanese brome are two to three inches tall, green, and actively growing is an effective method of limiting new seed production and the ability of these species to crowd out desirable grasses.

It is important to understand however, that due to an extensive bank of seeds already in the soil, one prescribed burn is not going to eliminate the problems associated with these weeds. Multiple treatments including herbicides, prescribed burning, and grazing will likely be required over a period of years for successful control.

Mob Grazing
Pre-season grazing is another option for cheatgrass and Japanese brome control. Heavy, pre-season grazing is cheap, much cheaper than chemical or even prescribed burning. Furthermore, cheatgrass and Japanese brome are grasses; and green grass is green grass when fuel and fodder are at all-time highs. So why not let grazing livestock perform your weed control for you?

Pre-season grazing to control annual weeds however, requires much more grazing pressure than your normal summer stocking rate can provide. Mob grazing is a grazing system that can provide the increase in grazing pressure needed to successfully control these weeds.

Pre-season mob grazing will not hurt your spring or summer grasses so long as heavy grazing ceases before desirable grasses get more than a couple inches tall. Spring-time cool-season grasses generally won’t start growing until early- to mid-May so as long as you pull cattle off pasture or at least back the grazing pressure down to summer stocking rate levels by this time no damage will be done.

When using mob grazing however, it is important not to let livestock linger in an area too long. Excessive grazing pressure over too much time can compact soil and damage plant bases. Let the mob clean the cheatgrass and Japanese brome in a grazing area up and keep them moving to fresh allotments. Livestock probably won’t clean up every single weed plant, but you can’t beat the cost of this weed control treatment.